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<p>Conductive metal-organic frameworks (MOFs), featuring atomically dispersed metal centers and well-defined intrinsic topological structures, offer high electrical conductivity without the need for additional carbonization processes. In this study, based on 2,3,6,7,10, 11-hexamiminotriphenyl (HITP), Co<sub>3</sub>(HITP)<sub>2</sub> and its Fe-doped derivative Co<sub>1.5</sub>Fe<sub>1.5</sub>(HITP)<sub>2</sub> were prepared through the one-step solvothermal approach. The results indicated Fe doping did not alter the two-dimensional morphology of the material, and a slight lattice contraction occurred upon Fe incorporation. Moreover, the successful incorporation of Fe and the formation of Fe–N<sub>4</sub> coordination structures with the HITP ligand led to a red shift in the C = N vibrational band and a 0.4&#xa0;eV decrease in the Co 2p binding energy. Furthermore, the pyridinic nitrogen content increased by 18%. Raman spectra revealed an increase in defect density upon Fe doping, as evidenced by an elevated I<sub>D</sub>/I<sub>G</sub> ratio (from 0.88 to 0.91). Electrochemical measurements demonstrated that Co<sub>1.5</sub>Fe<sub>1.5</sub>(HITP)<sub>2</sub> exhibited apparently improved ORR performance within 0.1&#xa0;M KOH solution versus Co<sub>3</sub>(HITP)<sub>2</sub>. Specifically, the half-wave potential showed a 40 mV positive shift (0.793&#xa0;V vs. 0.734&#xa0;V, vs. RHE), the limiting current density increased within 4.42–4.76&#xa0;mA/cm<sup>2</sup>, the electron transfer number rose within 2.2–3.9, and Tafel slope decreased from 112.35 mV·dec<sup>–1</sup> to 93.46 mV·dec<sup>–1</sup>. Mechanistic analysis revealed that the electronic synergy of Fe with Co optimized the electronic density at active centers, while an increased defect density facilitated further active site exposure, collectively accelerating ORR kinetics. Our results offer the new way to rationally design high-performance bimetallic MOF-based catalysts for ORR.</p>

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Oxygen reduction reaction catalytic activity of two-dimensional TM3(HITP)2 with Fe/Co bimetallic structure and its mechanism

  • 期刊论文

  • 发表日期：

    2026年4月14日

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  • Zan Gao

摘要

Conductive metal-organic frameworks (MOFs), featuring atomically dispersed metal centers and well-defined intrinsic topological structures, offer high electrical conductivity without the need for additional carbonization processes. In this study, based on 2,3,6,7,10, 11-hexamiminotriphenyl (HITP), Co3(HITP)2 and its Fe-doped derivative Co1.5Fe1.5(HITP)2 were prepared through the one-step solvothermal approach. The results indicated Fe doping did not alter the two-dimensional morphology of the material, and a slight lattice contraction occurred upon Fe incorporation. Moreover, the successful incorporation of Fe and the formation of Fe–N4 coordination structures with the HITP ligand led to a red shift in the C = N vibrational band and a 0.4 eV decrease in the Co 2p binding energy. Furthermore, the pyridinic nitrogen content increased by 18%. Raman spectra revealed an increase in defect density upon Fe doping, as evidenced by an elevated ID/IG ratio (from 0.88 to 0.91). Electrochemical measurements demonstrated that Co1.5Fe1.5(HITP)2 exhibited apparently improved ORR performance within 0.1 M KOH solution versus Co3(HITP)2. Specifically, the half-wave potential showed a 40 mV positive shift (0.793 V vs. 0.734 V, vs. RHE), the limiting current density increased within 4.42–4.76 mA/cm2, the electron transfer number rose within 2.2–3.9, and Tafel slope decreased from 112.35 mV·dec–1 to 93.46 mV·dec–1. Mechanistic analysis revealed that the electronic synergy of Fe with Co optimized the electronic density at active centers, while an increased defect density facilitated further active site exposure, collectively accelerating ORR kinetics. Our results offer the new way to rationally design high-performance bimetallic MOF-based catalysts for ORR.